Indra J. Das/ Small Fields (Page-1)

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ICRU-83: Guidelines and Compliance in IMRT

Indra J. Das, PhD, FAAPM, FACR, FASTRO Department of Radiation Oncology

New York University Langone Medicine Center New York, NY

Improving Dose Prescriptions for Safety, Reporting,

and Clinical Guideline Consistency Jean Moran, Univ of Michigan, Ann Arbor

Mark Langer, Indianian Univeristy, Indianapolis

IJDas (2)

ICRU:International Commission on Radiation Units and Measurements

1978 , ICRU-29; Dose specification for reporting external beam therapy with photon and electron beams.

1993, ICRU-50; Prescribing, recording and reporting photon beam therapy.

1999, ICRU-62; Prescribing, recording and reporting photon beam therapy (Supplement to ICRU 50).

IJDas (3) Dische et al, Radiother Oncol, 29, 287-293, 1993

Dose Prescription & Outcome

5% dose diff 5% dose diff

Isocenter dose

Isocenter dose

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IJDas (4) Brahme, Acta Oncologica, 36, 789-7923, 1997

Need for Dose Specification

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Pre

scri

ptio

n D

evia

tion:

(P

lann

ed/P

resc

ribe

d D

ose)

Patient Number

Minimum

Maximum

Median

Isocenter

Institution 1 Institution 2 Institution 3 Institution 4 Institution 5

Variations in doses in 803 patients among institutions

63%

46%

Das et al. J Natl Cancer Inst 100 (5), 300-3007, 2008

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D2% is defined as Maximum dose

D50% is Mean/median dose,

prescription dose and very close to

reference dose (ICRU-50)

D98%, considered as minimum dose

in PTV

HI = (D2% -D98%)/ D50%

Definition of sub volume with

overlaps

IMRT Dose Prescription: ICRU 83

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S S S wijk(Dopt-Dcal)2 = minimum

i,j,k

wijk= weight for constraint of an organ

Optimization & Cost Function

IJDas (8) ICRU-83, 2010

ICRU-83 DVH Parameters

IJDas (9) ICRU-81, 2010

ICRU-Definitions

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Minimization

Iteration, Search routine

Cost

Funct

ion

Gradient, Newtonian optimization

A

B

Iteration, Search routine

Cost

Funct

ion

Stochastic optimization

A

B

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Vo

lum

e (%

)

91 90 92 94 96 98 101 93 95 97 100 99 102 103 104 105

Dose (%)

106 107 108 109

D50%

D100% D98%

D95%

D2%

DD

A B

Concept of Dose Prescription

What should

be the dose

tolerance?

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0 500 1000 1500 2000 2500 3000 3500 4000 4500 5000

Dose

(%

)

Number of patients

D100

D98

D95

D50

D2

I-1 I-2 I-3 I-4 I-5 I-6 I-7 I-8 I-9 I-10

Dose Among Institutions

Das et al, Pr Radiat Oncol, 7, e145-c155, 2017

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90

100

110

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0 1 2 3 4 5 6 7 8 9 10 11 12

% D

ose

Institutions

D2%

D50%

D98%

Global Trends

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Dose

(%

)

Number of patients

D100

D98

D95

D50

Breast

Extr

e

mit

ies

Head & Neck Liv er

Pelvis Thorax

Oth er

Lung

Dose Distributions Among Sites

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60

70

80

90

100

110

120

130

140

Breast Extremity HN Liver Lung Pelvis Thorax Other

% D

ose

Treatment Site

D2%

D50%

D98%

Dose Trends in Site

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D100

D98

D95

D50

D2

0

5

10

15

20

25

90 95 100 105 110 115

Fre

quen

cy (

%)

Dose (%)

Das et al, Pr Radiat Oncol, 7, e145-c155, 2017

Frequency Distribution of Dose Parameters

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90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110

Fre

quen

cy (

%)

Dose (%)

I-1 D95I-1 D50I-2 D95I-2 D50I-3 D95I-3 D50I-4 D95I-4 D50I-5 D95I-5 D50I-6 D95I-6 D50I-7 D95I-7 D50I-8 D95

Das et al, Pr Radiat Oncol, 7, e145-c155, 2017

Frequency Distribution of D95 and D50

D95

D50

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Breast D50

Lung D50

Liver D50

H&N D50

Pelvis D50

Thorax D50

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40

90

93

96

99

10

2

10

5

10

8

11

1

11

4

11

7

12

0Fre

qu

ency

(%

)

Dose (%)

Frequency Distribution of D95 and D50 among Sites

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0

200

400

600

800

1000

1200

1400

0 1 2 3 4 5 6 7 8 9 10

Vo

lum

e (c

m3)

Institution

H&N

Das et al, Pr Radiat Oncol, 7, e145-c155, 2017

Target Volume Variations Among Institutions

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60

70

80

90

100

110

120

130

140

IMRT VMAT TOMO SBRT

Do

se (

%)

Treatment Techniques

D2D50D95D98D100

Variability Among Treatment Techniques

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Outcome and Clinical Trials

Ohri et al. JNCI, 105, 387-393, 2013

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Outcome With Excess Dose

Moore et al. IJROBP, 105, 387-393, 2013

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Outcome With Prostate Dose

Kalbashi et al. JAMA Oncol, 7, 896-906, 2015

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Conclusions Adoption of target volume nomenclature is extremely poor

and variable even after ICRU-50 (1993) for 3DCRT

ICRU-83 adoption is poor indicated in large variability in dose prescription/delivery in IMRT and even in academic institutions

Head & Neck and pelvis have better uniformity in dose prescription compared to other disease sites

Clinical trials should emphasize the need for uniformity in dose prescription for a meaningful treatment outcome

Mere ±10% dose difference has shown significant outcome difference

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Thanks